Strontium ranelate was by prescription , but it is no longer available due to cardiovascular/clot risks, in the EU. Strontium citrate is the only form in the US.

@callalloo I separate my calcium and magnesium and avoid any supplements that mix them. My doc agreed with what I read, that they compete with each other. I don't know why, if that is true, so many supplements have calcium and magnesium together, but to be on the safe side, I take them at least 2 hours apart.